The present invention relates to a protection element for a meshed energy supply network of a means of transport, in particular of an aircraft, a meshed energy supply network with such protection elements, a method for protecting such a meshed energy supply network and a computer program for executing the method.
Energy supply networks (also called on-board networks in means of transport) are used in a means of transport such as e.g., an aircraft, a ship, a submarine, a bus or a train to supply electrical energy to electrical recipients (consumers). Often the totality of all electrical components in the means of transport is described as the on-board network. The electrical components include, among other things, the cabling, control apparatuses, sensors, display elements (such as warning and indicator lamps, displays), actuators (such as electric motors, lamps and lighting systems), bus systems, energy stores (such as batteries and accumulators) and generators. Conventional on-board networks are normally constructed in a star shape in means of transport such as aircraft, i.e., each consumer is normally supplied with electrical energy from the generator or generators by its own line. To safeguard the conventional energy supply networks, each line to a consumer is often protected separately by overcurrent protection (e.g., a fuse). Higher-level supply lines (so-called feeder lines) are likewise protected by correspondingly larger fuses. If a fault (e.g., an earth fault) occurs in a supply line, the pertinent fuse responds and the consumer is separated from the energy supply network. Networks constructed in a star shape are reliably safeguarded thereby.
The demand for electrical energy in means of transport, such as aircraft, has increased steadily in the last few decades. This is due among other things to the fact that aircrafts, for example, are becoming ever bigger, electrical loads and functions have been added that replace pneumatic or hydraulic systems, and additional electrical consumers have been added due to growing comfort requirements of the passengers. Consideration is being given accordingly to using meshed energy supply networks (on-board networks) increasingly in means of transport, such as aircraft. A meshed energy supply network normally has a plurality of network nodes, which are each connected to one or more other network nodes. These meshed network structures are especially suitable for networks of high load densities, but can also be used in networks of low load density.
For the selective network protection of meshed energy supply networks in means of transport, such as aircraft, so-called distance or impedance protection is offered. In this, simple switches are used that in the event of a network error can separate the network error from the rest of the network. The conventional selective network protection system is constructed in a decentralized manner, i.e., no communication is necessary between the switches. For each switch, depending on the quotient of voltage and current following the occurrence of the fault, i.e., from the related impedance, a fixed trigger time is determined at which the switch opens (triggers) and thereby interrupts its connection to the network error. The impedance determined is dependent in this case on the line impedance and the length of the line to the network error. The greater the impedance, the greater also the trigger time. The result of this is that switches close to the fault trigger faster on account of the smaller impedance than switches remote from the fault with a correspondingly greater impedance. Due to the staggered triggering of the switches, the fault is separated, i.e., isolated from the rest of the network.